When a subject is both philosophically exciting and mathematically
complex, it’s easy to develop weird ideas about it, like quantum entanglement,
qubits and superposition. So, in this write-up, I have chosen to clear up some
common confusion about what these buzzwords mean. I am also recalled of “Virus”
in “3-Idiots” saying, “this is not a philosophy class, oon dou words ka mattlab
Superposition is something that we see in the routine affairs of our day
to day life. Imagine playing two notes on a guitar; the sound we hear is a
superposition of these two notes. Quantum superpositions are also made up of a
combination of states, with the key difference of performing a measurement.
Despite the system existing in a perfectly well-defined superposition state,
when we perform certain measurements on these systems we may get random
outcomes. So, the magic is actually observed as a special kind of quantum
randomness. Now, entanglement is the idea that we can’t describe two entangled
particles independent of each other. Their states are tied together in ways
that can’t be recreated in our classical world. If we measure one of them, we
might observe that it behaved randomly, but at the same time, it tells us what
to expect when measuring the other particle, in the same way. According to
researchers, this phenomenon of perfect correlation holds true even if we
measure the entangled particles at opposite ends of the galaxy.
Harnessing entanglement for computation is considered to be a crucial
ingredient for speeding up computation using quantum computers. Just like with
classical computing, we need a set of instructions that represent a
problem-solving approach (i.e. an algorithm), and a machine that can execute
those instructions (i.e. a computer). The fact that quantum computers can
actually create superpositions, entanglement, and other quantum effects means
that we can write algorithms in a new way than before. Qubits are fundamental
to quantum computing and are somewhat analogous to bits or binary digits in a
classical computer. Qubits can be in a “1” or “0” quantum state. But these can
also be in a superposition of the “1” and “0” states. However, when qubits are
measured, the result is always a “0” or a “1” although the probabilities of the
two outcomes, depends on the quantum state they were in.
All computing systems rely on a fundamental ability to store and
manipulate information. We are already experiencing tonnes of benefits everyday
by using the classical computers. Quantum computing refers to the new
breakthroughs in science by the use of quantum computers, which could spur the
development of more efficient devices and structures, to new machine learning
methods to diagnose illness and improve medication to save lives and even
improve our financial strategies to live well in retirement. For problems above
a certain size and complexity, classical computers can’t work well as these
don’t have enough computational power.
To stand a chance at solving such problems, say searching for dark
matter or building more stable silicon chips or solving an intricate business
problem, we needed a new kind of computing.
The idea of quantum computing was proposed by an American physicist Paul
Benioff in the early 1980’s. He is best known for his research in quantum
information theory describing the first quantum mechanical model of a computer.
This work has continued since then and has now encompassed quantum robots and
also the relationships between foundations in logic, Math’s and Physics.
Quantum computers have the potential to process exponentially more data as
compared to classical computers. These could also simulate things that a
classical computer could not. These perform the calculations based on the
probability of an object’s state before it is measured. A quantum computer
harnesses some of the mystical phenomena of quantum mechanics to deliver huge
leaps forward in processing the data. Until a few decades ago, quantum
computing was a purely theoretical subject, but today the real quantum
processors are being used by researchers all over the world to test out
algorithms for application in a wide variety of fields. The field of quantum
computing is a subfield of quantum information science. There are however, a
number of technical challenges in building a large scale quantum computer.
Sourcing the parts of quantum computer is very difficult. Quantum computers are
different from traditional computers based on transistors. These need Helium-3, a nuclear research
by-product and certain special cables that are made by a company in Japan. One
of the challenges associated with quantum computing is instability. Because
calculations are taking place at the quantum level, the slightest interference
from the environment can disrupt the process. That makes quantum computers very
expensive to build and maintain. A useful universal quantum computer – hardware
alone – comes in at least $10bn. Owing to these limitations, quantum computing
in full bloom is yet a distant dream. D-Wave, a Canadian company has taken the
lead in being the first to sell computers exploiting quantum effects. Similarly Google AI, a division of Google
dedicated solely to artificial intelligence, in partnership with the U.S
National Aeronautics and Space Administration (NASA) has claimed to have achieved
quantum supremacy as reported in a paper published on 23 oct 2019. While some
have disputed this claim, it is still a significant milestone in the history of
quantum computing. The goal that a
programmable quantum device can give a better insight in the problems of
science, engineering or business that classical computers practically cannot
do, irrespective of the relevance of the problem is what we mean by quantum
supremacy. Einstein had said that if quantum mechanics were correct, then the
world would be crazy. This is true in the sense that atoms or elementary
particles behave as if not real but representing a sea of possibilities and
potentialities rather than a single thing or a fact.
Qudsia Gani is Faculty (Physics), Cluster University Srinagar
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